smoothing, first and second derivates of spectra according to Savitsky-Golay
[result] = savgol(x,window,deriv, (degree))
a Div structure or a matrix of dimensions (n x q)
the window for the calculation; an odd integer >=5
the derivative: 0 (smoothing), 1 (first derivative) or 2 (second derivative)
the degree of the polynom; an integer between 2 and 5 ;by default degree=2
a Div structure containing the smoothed spectra
result.d0.d is a matrix of dimensions (n x q)
a Div structure containing the first derivates of the spectra
result.d1.d is a matrix of dimensions (n x q)
a Div structure containing the second derivates of the spectra
result.d2.d is a matrix of dimensions (n x q)